7.1 - Angle Relationships in Triangles

7.1 - Angle Relationships in
Triangles
Complete investigation on pg. 364
MPM1D ­ Mr. Robyn
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A
Vertex ­ point where two or more sides
meet. The vertex is always labelled with a
capital letter. Ex. A, B, C
B
C
Interior Angle ­ Angle formed on the inside
of a polygon by two sides meeting at the
vertex.
Exterior Angle ­ Angle formed on the
outside of a geometric shape by extending
one of the sides past the vertex.
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From the investigation:
1) The three interior angles of a triangle add up to 180 o
2) The exterior angles of a triangle add up to 360 o
3) The exterior angle and its interior angle add up to 180 o
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Example 1:
Find the measures of the exterior angles of
ABC.
D
A
E
B
70 o 40 o
C
F
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Example 2:
What is the measure of each exterior angle of an equilateral
triangle
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Homework:
Copy Key Concepts into your notes
from pg. 370
pg. 371 C1, C2 as a class
pg. 371 #1­6
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